In the coolant reservoirs of radiators of engines of automotive vehicles or a power generator, a considerable buildup of abnormal pressure and temperature conditions is a common occurrence. Further, these vehicles have less engine surface to dissipate the heat into the atmosphere. Therefore, in order to contain such excessive heat build-up problem, pressurized cooling systems are adopted. The pressurized cooling systems include a radiator with a coolant reservoir or a surge tank. The reservoir is provided with an opening, which is covered with a sealing cap, to facilitate filling and removal of coolant into and from the reservoir. Pressurized reservoirs of radiators are often provided with a closure cap or a valve which, when removed, allows the tank to release pressure and be filled with refilling coolant.
Whenever, it is desired to remove the sealing cap from the radiator and when the coolant is at a high temperature and under pressure, greater caution and care must be exercised, in removing the sealing cap from the radiator. Unless such care is used, the pressurized hot coolant is likely to be suddenly discharged from the spout of the radiator thereby causing serious burns to a person removing the cap and bystanders. More particularly, the sudden discharge of hot coolant becomes more acute, if the sealing cap is removed in a rapid and hurried manner, resulting in possible ejection of the sealing cap from the snout as a projectile.
Presently, dual O-ring sealing cap is adopted for radiator/surge tank, which releases, the excessive pressure from the reservoir, while the dual O-ring sealing cap is uninstalled, manually, from the spout. However, in case the sealing cap is rapidly uninstalled, resulting in premature opening or ejection of the sealing cap, thereby causing accidental discharge of hot coolant from the reservoir of the radiator. In other words, in such known dual O-ring sealing caps, a controlled and gradual release of residual positive pressure, that is built up in the reservoir having a hot coolant, till the positive pressure inside the reservoir matches with outer atmospheric pressure, becomes a limiting factor, especially whenever the dual O-ring sealing caps are uninstalled rapidly.
In another known metallic sealing cap, a non-rotatable lever is arranged on the top surface of the cap, which is lifted vertically, by a user, directly, to release the excess pressure from the reservoir, before the cap is uninstalled from the spout. In such arrangement, in view of the limited availability of the surface area of the cap, a considerable effort is required on the part of the user to lift the lever, without exposing the user to the hotter surfaces of the radiator and engine systems of an automotive. In this known arrangement of metallic sealing caps, in order to prevent accidental rotation of the cap, a tab is provided, which is locked with the spout of the radiator.
U.S. Pat. No. 5,108,001 discloses a pressure relief and venting closure cap for a filler neck of a vehicle gas or coolant system tank having an initial rotary drive which opens a vent valve in response to a differential movement between a cap shell and a vent valve actuator to vent the filler neck. In this disclosure, the retainer is pushed downwards to open the sealed vent valve to release the pressure. In addition, a biasing spring is used to retain the cam in its original position.
It is therefore, highly advantageous to provide a pressure-release sealing cap, with a pressure-release member, which is operable indirectly by a user, to release the excess pressure, in controlled and regulated manner, from a reservoir of an automotive vehicle radiator, prior to the removal of the pressure-release sealing cap.